title: Serum immunoglobulins in the infected and convalescent phases in community-acquired pneumonia.
abstract: BACKGROUND
  A population-based case-control study was designed to assess changes of serum levels of immunoglobulins and IgG subclasses between infected and convalescent phase in community-acquired pneumonia (CAP).
  
  
  METHODS
  Over a 2-year period, all subjects who were >14 years of age living in the Maresme region (Barcelona, Spain) diagnosed of CAP were registered. Controls were healthy subjects selected from the municipal census. Prognostic factors were assessed and serum levels of total IgG, IgA, IgM, and IgG subclasses were measured at diagnosis and 1 month later (cases).
  
  
  RESULTS
  We studied 171 patients with CAP and 90 controls. All immunoglobulins were significantly lower in cases than in controls. At diagnosis, 42.7% of cases showed low levels of some immunologic parameter, mainly total IgG and IgG2. Low immunoglobulin levels at diagnosis were more frequent in patients requiring in-patient care and in those with pneumonia of other etiology than Streptococcus pneumoniae. In the convalescent phase, 26 (23.6%) patients normalized immunological levels. In 27 (24.5%) cases, some parameter with low levels persisted especially in patients with etiology of CAP other than S. pneumoniae.
  
  
  CONCLUSIONS
  Low serum levels of immunoglobulins particularly total IgG and IgG2 were a common finding in patients with CAP compared to healthy controls. Low immunoglobulin levels may be related to CAP prognosis and persisted in the convalescent phase in one-fourth of cases.
authors.affiliation: Critical Care Service, Hospital de Mataró, Universitat Autònoma de Barcelona, CIBERES, Barcelona, Spain. Electronic address: mctorre@csdm.cat.
authors.forename: Mari C
authors.initials: MC
authors.lastname: de la Torre
authors.forename: Ignasi
authors.initials: I
authors.lastname: Bolíbar
authors.forename: Montse
authors.initials: M
authors.lastname: Vendrell
authors.forename: Javier
authors.initials: J
authors.lastname: de Gracia
authors.forename: Ester
authors.initials: E
authors.lastname: Vendrell
authors.forename: M José
authors.initials: MJ
authors.lastname: Rodrigo
authors.forename: Xavier
authors.initials: X
authors.lastname: Boquet
authors.forename: Pablo
authors.initials: P
authors.lastname: Torrebadella
authors.forename: Joan-Carles
authors.initials: JC
authors.lastname: Yébenes
authors.forename: Mateu
authors.initials: M
authors.lastname: Serra-Prat
authors.forename: Jordi
authors.initials: J
authors.lastname: Rello
authors.forename: Antoni
authors.initials: A
authors.lastname: Torres
authors.forename: Jordi
authors.initials: J
authors.lastname: Almirall
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D017714:Community-Acquired Infections / Q000097:blood; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism*; D007074:Immunoglobulin G / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000097:blood*; D055815:Young Adult
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G
keywords: Community-acquired pneumonia; IgG; IgG subclasses; Immunoglobulins; Prognosis